Field
Embodiments of the present disclosure generally relate to valves used to control the injection of chemicals, fluids and water for treatment of harmful depositions and erosion in tubing and around downhole tools.
Description of the Related Art
Chemical injection is the process of injecting fluid chemicals into the production stream of a well to control corrosion and harmful deposits in the tubing and tubing accessories during production. In a typical chemical injection installation, a chemical injection mandrel with a chemical injection valve is installed as part of the production-tubing string. Injection chemicals are pumped down to an inlet port of the chemical injection mandrel through the tubing/casing annulus or a dedicated chemical injection line by a chemical injection pump. The chemical injection valve opens to allow the injection chemicals into the tubing when the pressure of the injection chemical exceeds a predetermined valve opening pressure and closes when the pressure drops.
The chemical injection valves incur a large number of open/close cycles because the chemical injection valves open and close with every stroke of the piston in the chemical injection pump. Standard chemical injection valves use metal to metal seal. For example, a standard chemical injection valve uses a spring loaded stem mechanism with a ball and seat closure. When the valves perform a large number of open/close cycles, the valves may leak because the metal to metal sealing surfaces become damaged by erosion and contact loads. In addition, the conical surface of the seat does not provide constant sealing diameter, which results in an imprecise opening pressure. Elastomer seals sometimes are used on the outer diameter of the stem or the inner diameter of a bore in the seal to provide a constant sealing diameter and improve pressure regulation. However, the elastomer seals cannot survive a long period of time due to the flow erosion caused by high fluid discharge pressure and/or a large number of open/close cycles.
Therefore, there is a need for chemical injection valves with improved pressure regulation and/or improved erosion resistance.